The White House has issued new rules for how it will comply with a controversial law regarding al-Qaida suspects. The law requires the government to send many terrorism suspects into military custody, not into the hands of the FBI. And President Obama now says the law will not apply to U.S. citizens or legal residents captured on American soil or to people arrested by state and local police.

As NPR's Carrie Johnson reports, those broad exceptions could set off another fight in Congress.

CARRIE JOHNSON, BYLINE: The White House made no secret of its doubts about the defense law when Congress approved it last December. President Obama said it interfered with his authority and disrespected the ordinary court system which works best in many cases. But because the law included lots of perks for the military, the president decided not to veto it. Instead, this week, his administration announced it would interpret the law to include big exemptions for all kinds of terrorism suspects. Iowa Republican Senator Charles Grassley addressed the issue at a Judiciary Committee hearing today.

SENATOR CHARLES GRASSLEY: Between the bureaucratic requirements and the seven national security waivers, it is clear the provision will be seldom, if ever used on anyone, let alone a United States citizen.

JOHNSON: Other Republican senators, including Arizona's John McCain and South Carolina's Lindsey Graham, said they worry the White House was thumbing its nose at Congress. Graham says investigators need flexibility so they can get information that could help prevent terrorist plots without worrying about reading Miranda rights to suspects.

SENATOR LINDSEY GRAHAM: We just can't kill all these guys and be safe. When we capture somebody, it's a golden opportunity to find out about what the enemy is up to in future attacks.

SENATOR DIANNE FEINSTEIN: The argument that the pursuit of criminal charges could interfere with the gathering of intelligence from a terrorist suspect, I'm in a position where I see that it has not.

JOHNSON: That's California Democrat Dianne Feinstein. She leads the Senate Intelligence Committee. And she cited the notorious case of the so-called underwear bomber, Umar Farouk Abdulmutallab, to make her point.

FEINSTEIN: Abdulmutallab was Mirandized. It didn't stop him from pleading guilty. He's pled guilty, and he's serving a life sentence.

JOHNSON: Feinstein has some other concerns with the state of the law today. She's introduced a bill that would make it clear the government can't indefinitely detain on U.S. soil any Americans suspected of terrorism without criminal charges or trials. Legal experts say, under current law, that issue is up in the air. Steven Vladeck teaches law at American University.

STEPHEN VLADECK: Indeed if anything is actually clear about the status quo, it's its lack of certainty.

JOHNSON: But some national security lawyers say the government should keep things loose for those rare times when authorities might want to hold one of their own citizens. Steven Bradbury worked at the Justice Department in the Bush years.

STEVEN BRADBURY: There could well be extraordinary circumstances during an armed conflict when it may prove necessary to detain a U.S. citizen as an enemy combatant consistent with the laws of war.

JOHNSON: Al-Qaida is trying to attract people inside the U.S. to turn against their own government, Bradbury says. Bringing in the FBI means...

BRADBURY: Early administration of Miranda warnings, early access to courts, early access to defense counsel.

JOHNSON: Lorraine Bannai teaches law at Seattle University. She takes a different view.

JOHNSON: Members of the U.S. House have introduced a companion bill on indefinite detention to Feinstein's that could get a hearing there soon. Carrie Johnson, NPR News, Washington. Transcript provided by NPR, Copyright NPR.